/*
 * Copyright (c) 2000 jPOS.org.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *    "This product includes software developed by the jPOS project 
 *    (http://www.jpos.org/)". Alternately, this acknowledgment may 
 *    appear in the software itself, if and wherever such third-party 
 *    acknowledgments normally appear.
 *
 * 4. The names "jPOS" and "jPOS.org" must not be used to endorse 
 *    or promote products derived from this software without prior 
 *    written permission. For written permission, please contact 
 *    license@jpos.org.
 *
 * 5. Products derived from this software may not be called "jPOS",
 *    nor may "jPOS" appear in their name, without prior written
 *    permission of the jPOS project.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  
 * IN NO EVENT SHALL THE JPOS PROJECT OR ITS CONTRIBUTORS BE LIABLE FOR 
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the jPOS Project.  For more
 * information please see <http://www.jpos.org/>.
 */

package com.nasoft.util;

import java.util.Iterator;
import java.util.Vector;

/**
 * Peer class Logger forwards LogEvents generated by LogSources to LogListeners.
 * <br>
 * This little <a href="/doc/LoggerGuide.html">tutorial</a> give you additional
 * information on how to extend the jPOS's Logger subsystem.
 * 
 * @author apr@cs.com.uy
 * @version $Id: Logger.java,v 1.19 2003/10/13 10:46:16 apr Exp $
 * @see LogEvent
 * @see LogSource
 * @see LogListener
 * @see Loggeable
 * @see SimpleLogListener
 * @see RotateLogListener
 */
public class Logger
{
  String name;
  Vector listeners;

  public Logger()
  {
    super();
    listeners = new Vector();
    name = "";
  }

  public void addListener(LogListener l)
  {
    synchronized (listeners)
    {
      listeners.add(l);
    }
  }

  public void removeListener(LogListener l)
  {
    synchronized (listeners)
    {
      listeners.remove(l);
    }
  }

  public void removeAllListeners()
  {
    synchronized (listeners)
    {
      Iterator i = listeners.iterator();
      while (i.hasNext())
      {
        LogListener l = ((LogListener) i.next());
        if (l instanceof Destroyable)
        {
          ((Destroyable) l).destroy();
        }
      }
      listeners.clear();
    }
  }

  public static void log(LogEvent evt)
  {
    Logger l = ((LogSource) evt.getSource()).getLogger();
    if (l != null && l.hasListeners())
    {
      synchronized (l.listeners)
      {
        Iterator i = l.listeners.iterator();
        while (i.hasNext() && evt != null)
          evt = ((LogListener) i.next()).log(evt);
      }
    }
  }

  /**
   * associates this Logger with a name using NameRegistrar
   * 
   * @param name
   *          name to register
   * @see NameRegistrar
   */
  public void setName(String name)
  {
    this.name = name;
    NameRegistrar.register("logger." + name, this);
  }

  /**
   * destroy logger
   */
  public void destroy()
  {
    NameRegistrar.unregister("logger." + name);
    removeAllListeners();
  }

  /**
   * @return logger instance with given name. Creates one if necessary
   * @see NameRegistrar
   */
  public synchronized static Logger getLogger(String name)
  {
    Logger l;
    try
    {
      l = (Logger) NameRegistrar.get("logger." + name);
    } catch (NameRegistrar.NotFoundException e)
    {
      l = new Logger();
      l.setName(name);
    }
    return l;
  }

  /**
   * @return this logger's name ("" if no name was set)
   */
  public String getName()
  {
    return this.name;
  }

  /**
   * Used by heavy used methods to avoid LogEvent creation
   * 
   * @return true if Logger has associated LogListsners
   */
  public boolean hasListeners()
  {
    synchronized (listeners)
    {
      return listeners.size() > 0;
    }
  }
}
